thumb|right|Painting of Yi Xing from the Shingon Hassozō, a series of scrolls depicting the first eight patriarchs of the [[Shingon school of Buddhism. Japan, Kamakura Period (13th-14th century)]]

Yixing (, 683–727) was a Buddhist monk of the Tang dynasty, recognized for his accomplishments as an astronomer, a reformer of the calendar system, a specialist in the Yijing (), and a distinguished Buddhist figure with expertise in Esoteric Buddhism.

In the realm of secular affairs, Yixing gained prominence for his reforms to the imperial calendar and his construction of a celestial globe featuring a liquid-driven escapement, the first in a long tradition of Chinese astronomical clockworks. Within Buddhist circles, he is particularly remembered for his contributions to the translation of the Mahāvairocana-sūtra and for authoring the authoritative commentary on that scripture, the Darijing shu (T 1796). Due to his significant activities in both religious and secular spheres, a legendary portrayal of Yixing as a master astrologer and practitioner of astral magic developed during the late Tang period, leading to the attribution of several astrological works to him. This survey had many purposes. It was established in order to obtain new astronomical data that would aid in the prediction of solar eclipses. There were three observations done for each site, one for the height of polaris, one for the shadow lengths of summer, and one for the shadow lengths of winter. However, Yi Xing's mechanical achievements were built upon the knowledge and efforts of previous Chinese mechanical engineers, such as the statesman and master of gear systems Zhang Heng (78–139) of the Han dynasty, the mechanical engineer Ma Jun (200–265) of the Three Kingdoms, and the Daoist Li Lan (c. 450) of the Southern and Northern Dynasties period.

It was the earlier Chinese inventor Zhang Heng during the Han dynasty who was the first to apply hydraulic power (i.e. a waterwheel and water clock) in mechanically-driving and rotating his equatorial armillary sphere. The arrangement followed the model of a water-wheel using the drip of a clepsydra (see water clock), which ultimately exerted force on a lug to rotate toothed-gears on a polar-axis shaft. With this, the slow computational movement rotated the armillary sphere according to the recorded movements of the planets and stars. Yi Xing also owed much to the scholarly followers of Ma Jun, who had employed horizontal jack-wheels and other mechanical toys worked by waterwheels.

The British biochemist, historian, and sinologist Joseph Needham states (Wade–Giles spelling):

In regards to mercury instead of water (as noted in the quote above), the first to apply liquid mercury for motive power of an armillary sphere was Zhang Sixun in 979 AD (because mercury would not freeze during winter). During his age, the Song dynasty (960–1279) era historical text of the Song Shi mentions Yi Xing and the reason why his armillary sphere did not survive the ages after the Tang (Wade–Giles spelling):

Earlier Tang era historical texts of the 9th century have this to say of Yi Xing's work in astronomical instruments in the 8th century (Wade–Giles spelling):

Buddhist scholarship

Yi Xing wrote a commentary on the Mahavairocana Tantra. This work had a strong influence on the Japanese monk Kūkai and was key in his establishment of Shingon Buddhism.

In his honor

thumb|right|180px|Memorial Pagoda of Monk Yi Xing

At the Tiantai-Buddhist Guoqing Temple of Mount Tiantai in Zhejiang Province, there is a Chinese pagoda erected directly outside the temple known as the Memorial Pagoda of Monk Yi Xing. His tomb is also located on Mount Tiantai.

See also

  • List of Chinese people
  • List of inventors
  • List of mechanical engineers
  • Verge escapement
  • Villard de Honnecourt

Notes

References

  • Bowman, John S. (2000). Columbia Chronologies of Asian History and Culture. New York: Columbia University Press.
  • Fry, Tony (2001). The Architectural Theory Review: Archineering in Chinatime. Sydney: University of Sydney Press.
  • Ju, Zan, "Yixing". Encyclopedia of China (Religion Edition), 1st ed.
  • Needham, Joseph (1986). Science and Civilization in China: Volume 3. Taipei: Caves Books, Ltd.
  • Needham, Joseph (1986). Science and Civilization in China: Volume 4, Part 2. Taipei: Caves Books, Ltd.
  • Boscaro, Adriana (2003) Rethinking Japan: Social Sciences, Ideology and Thought. Routledge. 0-904404-79-x p. 330
  • Yi Xing at Chinaculture.org
  • Yi Xing's Tomb Tiantai Mountain
  • Yi Xing at the University of Maine